• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3C
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• pp.153-157
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• 2005

Frequency selective fading occurs due to the Doppler Effect in mobile communication systems. The performances of the systems are rapidly reduced due to effect of multiuser interference under frequency selective channels at DS-CDMA systems. To overcome these problems, we adopted the multi-carrier modulation techniques, and it is able to solve the frequency selective channel effects by means of these modulation techniques, and interference problems due to multiuser access are solved by means of multiuser detection techniques. In this paper, we proposed the blind MOE/PIC multiuser detection method which is composed of both the blind multiuser detection technique and parallel interference canceller. Thus, simulation results show that the proposed method performs better than conventional methods.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.3
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• pp.79-84
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• 2011

In this paper, we analyzed performance of vehicle detection for ITS (Intelligent Transport System) applications. We simulated the vehicle detection at Hi-Pass System is based on DSRC (Dedicated Short Range Communication). DSRC is a wireless network using ITS, including GPS (Global Positioning System) satellites in conjunction with the national transportation system. The system performance is evaluated in terms of bit error probability. In the simulation, the vehicle speed is set at 60 km/h and carrier frequency is 5.8 GHz. Wireless channel is modeled as the Rician fading channel. In the transmitter, the ASK (amplitude shift keying) modulation scheme is applied. From simulation results, we confirmed that performance of applied Alamouti scheme is better than other systems.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.568-573
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• 2002

In this paper, the Viterbi decoder containing new branch metrics of the squared Euclidean distance with multiple order phase differences is introduced in order to improve the bit error rate (BER) in the differential detection of the trellis-coded MDPSK-OFDM. The proposed Viterbi decoder is conceptually same as the Continuous multiple phase differential detection method that uses the branch metric with multiple phase differences. Also, we describe the Viterbi algorithm in order to use this branch metrics. Our study shows that such a Viterbi decoder improves BER performance without sacrificing bandwidth and power efficiency Also. the proposed algorithm ran be used in the single carrier modulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4C
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• pp.358-363
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• 2010

In IEEE 802.15.4a IR-UWB (Impulse Radio Ultra Wideband) systems, it is crucial to acquire initial carrier/timing synchronization and estimate channel response by exploiting the SYNC symbols embedded in each packet. On the other hand, it is also crucial to detect the SFD pattern followed by the header and data symbols to reliably extract the information contained in the packet. In this paper, we propose a reliable SFD detection scheme utilizing some surplus SYNC symbols in addition to SFD symbols to improve the SFD detection performance.

• Food Science and Biotechnology
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• v.17 no.4
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• pp.829-832
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• 2008

A multiplex polymerase chain reaction (PCR) method was developed to simultaneously detect 4 varieties of genetically modified (GM) cotton. The event-specific primers were used to distinguish the 4 varieties of GM cotton (MON1445, MON15985, MON88913, and LLcotton25) using multiplex PCR. The acyl carrier protein 1 (Acp1) gene was used as an endogenous reference gene of cotton in the PCR detection. The primer pair Acp1-AF/AR containing a 99 bp amplicon was used to amplify the Acp1 gene and no amplified product was observed in any of the 13 different plants used as templates. This multiplex PCR method allowed for the detection of event-specific targets in a genomic DNA mixture of up to 1% GM cotton containing MON1445, MON15985, MON88913, and LLcotton25.

• Journal of the Korean institute of surface engineering
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• v.55 no.3
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• pp.156-163
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• 2022

An ammonium ion with a size and charge similar to that of potassium can bind to valinomycin, which is used as an ion carrier for potassium, and cause a meaningful interference effect on the detection of potassium ions. Currently, there are few ion sensors that correct the interference effect of ammonium ions, and there are few studies that specifically suggest the mechanism of the interference effect. By fabricating a SPCE-based potassium ion-selective electrode, the electromotive force was measured in the concentration range of potassium in the nutrient solution, and the linear range was measured to be 10^-5 to 10^-2 M, and the detection limit was 10^-5.19 M. And the interference phenomenon of the potassium sensor was investigated in the concentration range of ammonium ions present in the nutrient solution. Therefore, a data-based analysis strategy using deep learning was presented as a method to minimize the interference effect.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.2
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• pp.583-599
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• 2015

We apply the Bayesian matching pursuit (BMP) algorithm to the estimation of time-frequency selective channels in orthogonal frequency division multiplexing (OFDM) systems. By exploiting prior statistics and sparse characteristics of propagation channels, the Bayesian method provides a more accurate and efficient detection of the channel status information (CSI) than do conventional sparse channel estimation methods that are based on compressive sensing (CS) technologies. Using a reasonable approximation of the system model and a skillfully designed pilot arrangement, the proposed estimation scheme is able to address the Doppler-induced inter-carrier interference (ICI) with a relatively low complexity. Moreover, to further reduce the computational cost of the channel estimation, we make some modifications to the BMP algorithm. The modified algorithm can make good use of the group-sparse structure of doubly selective channels and thus reconstruct the CSI more efficiently than does the original BMP algorithm, which treats the sparse signals in the conventional manner and ignores the specific structure of their sparsity patterns. Numerical results demonstrate that the proposed Bayesian estimation has a good performance over rapidly time-varying channels.

• Journal of Positioning, Navigation, and Timing
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• v.6 no.4
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• pp.149-157
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• 2017

In this study, a system that precisely determines the heave of ship hull was designed using time-differenced GNSS carrier phase measurement, and the performance was examined. First, a technique that calculates precise position relative to the original position based on TDCP measurement for point positioning using only one receiver was implemented. Second, to eliminate the long-cycle drift error occurring due to the measurement error that has not been completely removed by time-differencing, an easily implementable high-pass filter was designed, and the optimum coefficient was determined through an experiment. In a static experiment based on the precise heave measurement system implemented using low-cost commercial GNSS receiver and PC, the heave could be measured with a precision of 2 cm standard deviation. In addition, in a dynamic experiment where it moved up and down with an amplitude of 48 cm and a cycle of 20 seconds, precise heave without drift error could be determined. The system proposed in this study can be easily used for many applications, such as the altitude correction of fish detection radar.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.186-186
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• 2000

In the GPS/DR integrated system, the GPS position(or velocity) is used to compensate the DR output and to calibrate errors in the DR sensor. This synergistic relationship ensures that the calibrated DR accuracy can be maintained even when the GPS signal is blocked. Because of the observability problem, however, the DR sensors are not sufficiently calibrated when the vehicle speed is low. This problem can be solved if we use a multi-antenna GPS receiver for attitude determination instead of conventional one. This paper designs a two-antenna GPS receiver integrated with DR sensors. The proposed integration system has three remarkable features. First, the DR sensor can be calibrated regardless of the vehicle speed with the aid of two-antenna GPS receiver. Secondly, the search space of integer ambiguities in GPS carrier-phase measurements is reduced to a part of the surface of the sphere using DR heading. Thirdly, the detection resolution of cycle-slips in GPS carrier-phase measurements is improved with the aid of DR heading. From the experimental result, it is shown that the search grace is drastically reduced to about 3120 of the non-aided case and the cycle-slips of 1 or half cycle can be detected.

• Korean Journal of Adult Nursing
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• v.21 no.4
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• pp.435-445
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• 2009

Purpose: This study was to examine whether VRE infection control strategies have an effect on the decrease in incidence rates for VRE acquisition and VRE nosocomial infection in ICU. Methods: All the patients were examined for VRE carriers on ICU admission. Among them, patients hospitalized for over 48 hours were investigated for VRE acquisition rates and VRE nosocomial infection rate using VRE infection control strategies in ICU for the experimental group from September 2007 to April 2008. Before that, incidence of VRE acquisition and VRE nosocomial infection for the control group without Intervention were investigated from May to August 2007 retrospectively. Results: VRE acquisition rate in clinical specimens was 0.6% in the experimental group, that was significantly lower when compared to the control group. VRE carrier rate at admission to ICU was 15.4%. Out of 182 VRE carriers, 180 patients were identified by the active surveillance culture. Conclusion: These results suggested that active surveillance culture at admission was considered to be an essential measure for detection of VRE carrier. But without strict isolation and adherence rating after each intervention, hand washing and contact isolation alone did not significantly decrease VRE nosocomial infection, although it did significantly decrease incidence of VRE acquired from clinical specimen.